In a process for the removal of hydrogen chloride and/or sulfur oxides from a landfill gas stream, which contains impurities such as siloxanes, H.sub.2S, organic and inorganic sulfides and volatile organic compounds (VOCs), the heated gas is passed through a siloxane removal bed, where siloxanes are absorbed and then through one or more sulfur removal beds, where hydrogen sulfide and/or organic sulfides are absorbed. The effluent is passed through a reactor containing an oxidation catalyst enabling catalytic oxidation of VOCs, organic and inorganic CI- and/or S-containing compounds, COS and CS.sub.2 to their respective combustion products, and finally the effluent from the reactor is passed through one or more beds, where hydrogen chloride and/or sulfur oxides are absorbed.

Through the procedures of pretreatment, temperature swing adsorption (TSA) coarse desorption, pressure swing adsorption (PSA) purification and hydrogen purification, the hydrogenous waste gas from various procedures in the manufacturing process of semiconductor (especially silicon wafer), including the off-gas from chemical vapor deposition (CVD), doping (diffusion and ion implantation), photolithography and cleaning, the combusted and washed discharged gas of the off-gas in other procedures after field treatment and centralized treatment, or the hydrogenous waste gas entering the hydrogen discharge system are purified to meet the standard for the electronic grade hydrogen required for the manufacturing process of semiconductor, the recycling of hydrogen resources is realized, and the yield of hydrogen is greater than or equal to 70-85%. The present invention solves the technical difficulty the normal-pressure waste hydrogen recovered in the manufacturing process of semiconductor can't be returned to the manufacturing process of semiconductor for reuse.

Disclosed is a method of adding a feed medium into a bioprocess. The method includes receiving a stream of CO2-rich gas; treating the stream of CO2-rich gas to remove impurities therefrom; preparing an aqueous mixture for absorbing carbon dioxide, the aqueous mixture having at least one inorganic nitrogen compound in a range of 0.1-50 wt % of the aqueous mixture, the at least one inorganic nitrogen compound is a nitrogen source for microorganisms; absorbing carbon dioxide from the stream of CO2-rich gas into the aqueous mixture, the aqueous mixture with absorbed carbon dioxide forming a feed medium; and adding the feed medium into a bioprocess.

A heated inlet tube for use in a wet scrubber is disclosed. In one embodiment, the heated inlet tube comprises a heated tube concentric to the inlet tube to which a heated gas is applied thereby maintaining temperature of a waste gas stream as it flows through the inlet tube. In a further embodiment, an insulating tube concentrically surrounds the heated tube to further maintain the temperature of the waste gas stream.

The invention relates to a process for recovering methane from digester biogas or landfill gas. More specifically, the invention pertains to biomethane production that substantially removes carbon dioxide from a digester biogas or landfill gas using first, second, and third purification stages each comprising one or more membranes selective for carbon dioxide over methane. A retentate from the first stage is separated by the one more membranes of the second stage into a second state retentate, forming a biomethane product gas. A permeate from the first stage is separated by the one or more membranes of the third stage into a third stage retentate and a third stage permeate. Recovery of methane from the biogas is boosted by feeding the third stage retentate to the first purification stage. The recovery may be optionally further boosted by compressing the second stage permeate with the biogas at a main compressor.

In a process for the removal of siloxanes from biogas streams, especially a landfill gas stream or a gas stream from anaerobic digesters, the gas stream is first passed through a conventional siloxane removing unit to remove the majority of the siloxanes and subsequently passed over a selected catalyst with polishing effect, thereby removing remaining traces of siloxanes. The catalyst with polishing effect is chosen from i.a. zeolites, porous silica, titania and various metals on alumina or titania.

An air separation system includes an air separation module configured to receive feed air and separate the feed air into nitrogen-enriched air and oxygen-enriched air, a nitrogen-enriched air line for transporting the nitrogen-enriched air from the air separation module to a fuel tank for inerting, an oxygen sensing line connected to the nitrogen-enriched air line, a gas adsorption filter located in the oxygen sensing line, and an oxygen sensor downstream of the gas adsorption filter in the oxygen sensing line.

A reheating collection device for a gas phase process is provided with a container elongated in an axial direction along an axis to define a chamber, an inflow path and an exhaust path respectively in communication with the chamber and apart in the axial direction from each other, and a heater heating the chamber between the inflow path and the exhaust path.

Oxygen is removed from a gas feed such as a landfill gas, a digester gas or an industrial CO.sub.2 off-gas by removing sulfur-containing compounds and siloxanes from the feed gas, heating the feed gas, injecting one or more reactants for oxygen conversion into the heated feed gas, carrying out a selective catalytic oxygen conversion in at least onesuitable reactor and cleaning the resulting oxygen-depleted gas. The reactants to be injected comprise one or more of H.sub.2, CO, ammonia, urea, methanol, ethanol and dimethylether (DME).

A method for the purification of a raw gas stream by selective catalytic oxidation, in which organic and inorganic sulfur compounds, halogenated and non-halogenated volatile organic compounds are selectively oxidized without substantially oxidizing the lower hydrocarbons and the sulfur containing compounds present in the gas to sulfur trioxide and excess of oxygen is removed by oxidation of lower alcohols, ethers or hydrogen added to the raw gas stream upstream the catalytic oxidation.